One of the most glamorous creatures ever to grace the silver screen is back in pictures at the National Portrait Gallery in Washington, D.C. A dazzling new exhibition features dozens of photographs of the seductive, German-born movie star Marlene Dietrich.

Dietrich's legs were so famous that her studio insured them, and you can see why in the big photograph Milton Greene took of her in 1952. It shows the actress sitting, her face covered by a curtain of blonde hair. She's bending over her long, shapely, crossed and extremely exposed legs — legs so shapely that she shaped them in the photo, writing notes on the contact sheet about touch-ups.

As a movie star, Dietrich was known for controlling her image. But a very early photograph from 1918 shows her as a slightly pudgy Berlin schoolgirl with a big black bow in her hair and big lace collar. Exhibition curator Kate Lemay says, "This is a very sweet, innocent [teenage] Marlene Dietrich who had recently changed her name." (She was born Marie Magdalene Dietrich.) But on closer inspection, she doesn't look so innocent.

"She has a curl escaping her hair," Lemay says. "At the time, hair being brought all the way up off your neck was the sign of a good girl with good family, and Dietrich let that curl escape. She's already declaring her independence."

The teenager also has the eyes of a seductress: Her lids are a bit lowered and she's looking straight at us, daring us not to notice.

By the time World War II rolls around, Dietrich is a huge star. One photo, taken while entertaining American troops, shows her standing in a sea of soldiers. Her skin-tight sequined gown makes her look like a mermaid. "She's in her element," Lemay says. "She is flirting, and probably the best kind of flirt anyone's ever seen. She's just having the time of her life."

By then, Dietrich had made The Blue Angel (1930), in which she sings what became her signature song, "Falling in Love Again"; Blonde Venus (1932), in which she sings "Hot Voodoo"; and Morocco (1930), in which she tromps through the desert in sling-back pumps and kisses a woman. All those films were directed by Josef von Sternberg, her Pygmalion: He slimmed her down, penciled in her eyebrows and lit her into a femme fatale.

"He knew how to transform a young woman who had beautiful eyes, but maybe not the most perfect nose and some flaws," Lemay says. "And he lit her from 4 feet above her head and from the right side of her face with specific soft lighting. She was transformed into this incredible magnet for the eye."

She took that lesson from the director and applied it for the rest of her life. Bathed in light and made up to perfection, Dietrich often wore ties, top hats and tuxedos. "She dressed in menswear, and she pioneered dressing in menswear in the '20s and '30s," Lemay says. "She was the first cross-dressing woman to do so for a large audience."

Shocking? It certainly was. But according to Lemay, "Dietrich made it palatable." She says that's what made her want to put this exhibition together: "This is 1930 and American audiences are conservative, and yet here we have this German-born actor who's presenting an androgynous image and kissing a woman onstage. That's incredible."

So how did she get away with it?

"She was just really charismatic," Lemay says. "And she never apologized. When people did criticize her and ask her why she would dare do such a thing, she just let it roll off her back. She really did not apologize."

Dietrich's image changed over the years (though her lighting didn't). She became more relaxed in films, downright funny, even. In Destry Rides Again, a 1939 Western with James Stewart, she played a rollicking saloon girl in boots, a cowboy hat and a spangled vest (can't give up the glitter). By then she had applied for American citizenship, and adopted big American smiles.

In 1955, the scandal magazine Confidential published an article with the headline "You've Heard Lots About Marlene But You Haven't Heard It All." (The National Portrait Gallery show has the magazine on display.) Dietrich — who was married with a daughter, and had lots of lovers — was outed as bisexual. Few in her adoring public had a clue. In today's age of social media, a secret like that couldn't be kept for long; but in Dietrich's day, stars and studios had secrets that stuck.

How did the great, glamorous actress react to being outed? We don't know for sure, but Lemay's guess is she wouldn't have cared. "I really do believe she was unapologetic and just thought that was their problem."

Dietrich was 90 when she died in 1992. In her last several years, she had stopped going out in public. Her looks had faded, and breaks in those gorgeous legs kept her bedridden. But she stayed in touch with friends by telephone, and her image (and uber-confidence) blazed on screens and in memories for decades.